1. Field of the Invention
The present invention relates to a despin device and, more particularly, to a despin device mounted to an object spinning at a high speed to reduce an axial spinning speed of the object at an appropriate time.
2. Description of the Related Art
In space missions, originally fixed modules of a flying vehicle can be separated from each other, for instance, the departure of a payload (such as a satellite) from a rocket, or the activation of solar cell panels on a satellite.
Since an ordinary flying vehicle does not have attitude control, the flying vehicle often has to spin about its axis (at a speed of about 2-5 revolutions per second) during the flight to compensate asymmetric or residual propulsion, thereby increasing the flying stability of the flying vehicle. However, after the booster of the flying vehicle has stopped, it is difficult to control the trajectory of the payload under spinning together with the flying vehicle at a high speed such that the payload (such as a satellite or experimental equipment) often cannot be properly released to perform the mission. Thus, effective despin operation must be carried out on the flying vehicle to stabilize the flying vehicle. Therefore, the payload can be smoothly separated.
Taking a rocket as an example, the despin operation can be achieved by a yo-yo despin device. The conventional despin device includes a central base mounted between two rocket bodies, and a plurality of cables is provided to connect a plurality of masses, respectively. The cables are evenly wrapped around the central base. The masses are released at an appropriate time and move away from the central base due to the centrifugal force through the central base spinning together with the rocket bodies. The masses and cables are gradually deployed to generate an angular momentum contrary to the spin direction. Due to the laws of conservation of kinetic energy and momentum, the contrary angular momentum compels central base to despin.
However, since the cables of the conventional despin device are fixed to the central base, when each cable wrapped around the central base is drawn by the corresponding mass and is released to the final stage, the masses that continuously spin will cause the cables to rewrape. Thus, the masses may hit and damage the central base. As a result, this may lead to the instability of rocket and the trajectory deviation of payload after separating from the rocket. Thus, improvement to the conventional despin device is required.
Besides, the high speed of flying vehicle always induces heat flux at the vehicle surface. The heat flux may damage the conventional yo-yo despin system (such as cables, joints and electronic board.). Thus, the improvement of heat protection design (such as an outer rotational ring) is also required.